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Questions tagged [open-closed-principle]

The OCP is often introduced as "Software entities [...] should be open for extension, but closed for modification" (see detailed tag info for references).

Questions about the Open-Closed-Principle, as it was described by several authors mentioned in the Wikipedia article.

This is one of the SOLID principles.

69 questions
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LSP vs OCP / Liskov Substitution VS Open Close

I am trying to understand the SOLID principles of OOP and I've come to the conclusion that LSP and OCP have some similarities (if not to say more). the open/closed principle states "software entities (classes, modules, functions, etc.) should be…
Kolyunya
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Is overriding Object.finalize() really bad?

The main two arguments against overriding Object.finalize() is that: You don't get to decide when it's called. It may not get called at all. If I understand this correctly, I don't think those are good enough reasons to hate Object.finalize() so…
user138956
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Why does(/did) Bertrand Meyer think subclassing is the only way to extend a "closed" module?

In Meyer's Object-Oriented Software Construction (1988) he defines the open/closed principle as follows: A module will be said to be open if it is still available for extension. For example, it should be possible to add fields to the data…
David Moles
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Is it ok to inherit a class without adding anything to the child, to respect the Open Closed principle?

To clarify the question, here is my context (or something very similar). I have an interface, that I call IDataSource. The implementing classes contain information to retrieve data. So I have multiple classes implementing it, let's say FileSource,…
Kilazur
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Do mocks violate the Open/Closed principle?

Some time ago I read, on a Stack Overflow answer that I can't find, a sentence that explained that you should test public APIs, and the author said that you should test interfaces. The author also explained that if a method implementation changed,…
Christopher Francisco
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Does TDD contradict the open-closed principle?

My understanding of the TDD methodology is that (failing) test cases are written promptly after finalizing the requirements. My understanding of the open-closed principle (in the context of OOP) is to structure the class hierarchy so that any new…
Vorac
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7 answers

Refactoring and Open / Closed principle

I have recently being reading a web site about clean code development (I do not put a link here because it is not in English). One of the principles advertised by this site is the Open Closed Principle: each software component should be open for…
Giorgio
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Is overloading an example of the Open/closed principle?

Wikipedia says "software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification" The word functions caught my eyes, and I now wonder if we can assume that creating an overload for a method can be…
Saeed Neamati
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Liskov's substitution principle : If subtype has some extra behaviour implemented, which is not present in type, then is this violation of LSP?

In my quest to write better, cleaner code, I am learning about SOLID principles. In this, LSP is proving to be little difficult to grasp properly. My doubt is what if I have some extra methods in my subtype, S, which were not there in type, T, will…
user270386
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Static factory method in base class

An increasingly popular definition of factory method is: a static method of a class that returns an object of that class' type. But unlike a constructor, the actual object it returns might be an instance of a subclass. From :…
q126y
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How do I make this Open/Closed example also obey Single-Responsibility?

This is a simple example, but it reflects a tension between SOLID principles that I often find myself struggling with. A popular example of the Open/Closed Principle (e.g. [1], [2]) imagines that you have many Shape classes, and a drawShape()…
Standback
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In DDD, how do I persist an aggregate containing polymorphism

I've been developing applications according to the principles of DDD for a while now, and, as many, I often run into issues when it comes to persisting an aggregate. One of the main advantages of DDD is that it allows me to use the full power of OO…
Joeri Hendrickx
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Is "avoid feature envy" violating "open closed principle"?

After reading What is a" feature envy" code and why is it considered a code smell?" I know the following code is suffering from "feature envy": public class Garden{ public float width; public float height; } public…
wcminipgasker2023
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Open Closed principle in design patterns

I am bit confused about how Open Closed principle can be applied in real life. Requirement in any business changes over the time. According to Open-Closed principle you should extend the class instead modifying the existing class. To me every time…
parag
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Difficulty making this class open-closed

Here is my problem: I want to read input from different HID devices such as a gamepad, racing well, joystick, etc. Pretty much any game controller. The issue is that they all have different inputs. The gamepad has buttons, switches and sticks while…
Mihai Bratulescu
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